Three Mars Missions to Launch in Late 1996

THREE MARS MISSIONS TO LAUNCH IN LATE 1996

The United States and Russia return to Mars this fall
with the launch of three missions destined to explore Earth's
planetary neighbor in greater detail than has ever before
been accomplished.

NASA's Mars Global Surveyor and Mars Pathfinder and
Russia's Mars '96 mission are scheduled for three separate
launches in November and December 1996. Mars Global Surveyor,
an orbiter carrying six scientific instruments to study the
atmosphere, surface and interior of Mars, will be launched
Nov. 6. It will be followed by Russia's Mars '96, an orbiter
carrying 12 instruments plus two small landers and two
penetrators, which will lift off Nov. 16. Mars Pathfinder
will carry a lander and small rover robot when it is lofted
into space Dec. 2.

Launch of the NASA spacecraft marks the beginning of a
new era in Mars exploration and an ambitious new initiative
by the United States to send pairs of spacecraft to the red
planet every 26 months through the year 2005. NASA's new
decade-long program of robotic exploration -- known as the
Mars Surveyor program -- takes the next step in expanding
scientists' knowledge of Mars. The program is focused on
three major areas of investigation: the search for evidence
of past life on Mars; understanding the Martian climate and
its lessons for the past and future of Earth's climate; and
understanding the geology and resources that could be used to
support future human missions to Mars.

The unifying theme of the Mars exploration program is
the search for water, which is a key requirement for life, a
driver of climate and a vital resource. Early missions will
thus focus partially on finding and understanding the past
and present state of water on Mars. Mars Global Surveyor and
Mars Pathfinder will be the forerunners in this quest,
becoming the precursors to a series of missions that may
culminate in the first few years of the next century with
robotic return of a Martian soil sample to Earth, followed by
eventual human exploration.

Continuing Exploration Program

NASA's 1996 missions to Mars further the global
explorations of the planet begun in 1965 with the Mariner 4
mission to Mars and continued in the mid-'70s by the Viking
lander missions.

From earlier investigations, scientists have compiled a
portrait of Mars full of stark contrasts. Mars' surface
features range from ancient, cratered terrain like Earth's
Moon to immense volcanoes that would dwarf Mt. Everest and a
canyon that would stretch across the United States.

Mars' atmosphere is less than 1 percent as thick as
Earth's, but there are permanent polar caps with reservoirs
of water ice. Closeup shots of Mars' terrain resemble that of
an Earthly desert, with surface features that look like river
channels carved long ago by flowing water.

The next step in Mars exploration, according to
scientists, is to obtain an overview of the entire planet and
to verify remote observations with measurements taken from
the ground. Mars Global Surveyor is designed to study the
atmosphere, surface and interior systematically over a full
Martian year. The Russian Mars '96 orbiter has similar
objectives, but will also characterize the uppermost
atmosphere and its interactions with the solar wind.

To obtain "ground truth" -- observations on the surface
verifying those made from space -- the Russian Mars '96
spacecraft will deploy two landers that will touch down in
the northern hemisphere in a region called Amazonis Planitia
and two penetrators that will impact and lodge themselves
anywhere from 3 to 20 feet (1 to 6 meters) underground. These
probes will furnish details of the atmosphere and surface at
the specific locations in which they land. NASA is
contributing two experiments to Mars '96: the Mars Oxidation
Experiment, which will measure the oxidation rate of the
Martian environment, and the Tissue-Equivalent Proportional
Counter, which will study the radiation environment in
interplanetary space and near Mars.

Mars Pathfinder will deploy a mobile rover that will
characterize rocks and soil in a landing area over hundreds
of square meters (yards) on Mars. Pathfinder's instruments
and mobile rover are designed to provide an in-depth portrait
of Martian rocks and surface materials over a relatively
large landing area, thereby giving scientists an immediate
look at the crustal materials that make up the red planet.

Pathfinder Arrival in July 1997

Although the last to leave Earth, Mars Pathfinder takes
a shorter flight path and will be the first of the three
spacecraft to arrive at Mars, touching down in Ares Vallis on
July 4, 1997.

Pathfinder is designed to demonstrate an innovative
approach to landing a spacecraft and rover on the surface of
Mars. Pathfinder will dive through the upper atmosphere of
Mars on a parachute, then inflate a huge cocoon of airbags to
cushion its impact. The spacecraft will collect engineering
and atmospheric science data along its descent to the ground.

The primary objective of the mission is to test this
low-cost method of delivering a spacecraft, science payload
and free-ranging rover to the surface of the red planet.
Landers and rovers of the future will share the heritage of
spacecraft designs and technologies that evolve from this
pathfinding mission.

Once on the surface, the lander's first task will be to
transmit engineering and science data collected during
descent through the thin atmosphere of Mars. Then its camera
will take a panoramic image of its surroundings and begin
transmitting the data directly to Earth at a few thousand
bits per second. Much of Pathfinder's mission after this will
be focused on collecting atmospheric and surface composition
data, and supporting the rover by storing and transmitting
images captured by its cameras. Pathfinder's nominal mission
lifetime is approximately 30 "sols," or Martian days (about
the same number of Earth days).

Pathfinder's rover, Sojourner, will be carried to Mars
in a stowed configuration with its chassis and wheels folded
up like an accordion. Once its solar cells are exposed to the
Sun, the rover will power up and stand to its full height
before leaving the lander. Driving off onto the floor of an
ancient flood plain believed to contain a wide variety of
rocks, Sojourner will explore the surface independently,
relying on the lander primarily for communications with
Earth.

Mars Global Surveyor and Mars '96

Two months later, NASA's Mars Global Surveyor and
Russia's Mars '96 orbiter will arrive at Mars on September 11
and 12, 1997, respectively.

At first, Mars Global Surveyor will be in a highly
elliptical orbit and spend four months dipping lower and
lower into Mars' upper atmosphere using a technique called
aerobraking to bring it into a low-altitude, nearly circular
mapping orbit over the poles. By March 1998, Surveyor will be
ready to begin data collection, compiling a systematic
database as it surveys the Martian landscape and photographs
unique features, such as the polar caps and Mars' network of
sinuous, intertwining river channels.

Mars '96 carries a dozen instruments and a dozen smaller
devices designed to study the evolution of the Martian
atmosphere, surface and interior. In addition to
meteorological and seismic instruments, the spacecraft
carries instruments to image the Martian surface, explore the
chemistry and water content of rocks and attempt to detect
and measure the Martian magnetic field.